(1) Field of the Invention
The present invention relates to a structure for mounting a hook bracket to a bumper reinforce and a bumper structure.
(2) Description of the Related Art
A hook attached to an automobile is mainly used to tow another vehicle or used as a tie-down for securing the automobile to a ship when the automobile is placed on the ship. A great tensile load is applied to the hook in a forward direction or in a forward-downward direction. When an aluminum alloy extrusion having a hollow cross-section was introduced as a bumper reinforce, high rigidity of the hollow cross-section was used to propose a mount structure that is obtained by penetrating a hook bracket through a hole in front and rear walls of the bumper reinforce and welding the hook bracket to the front and rear walls.
According to Japanese Patent No. 4229388 (FIGS. 1 and 2), a hook bracket that is formed of an aluminum alloy extrusion and provided with a flange placed near the front end of a shaft portion and at the left and right of the rear end of the shaft portion is penetrated through a hole in the front and rear walls of a bumper reinforce and fillet-welded to the front and rear walls. In order to provide improved towing performance, a mount structure for the hook bracket is formed by bringing the flange near the front end of the hook bracket into contact with the rear surface of the front wall and bringing the flanges at the rear end into contact with the rear surface of the rear wall.
According to Japanese Patent No. 5374431, a hook bracket that is formed of an aluminum alloy extrusion and provided with an upward protruding rib near the front end of a shaft portion is penetrated through a hole in the front and rear walls of a bumper reinforce and fillet-welded to the front and rear walls. The direction of hook bracket extrusion is parallel to the longitudinal direction of the bumper reinforce. In order to provide improved towing performance particularly during a tie-down period, a mount structure for the hook bracket is formed by welding the rim of the rib to the front wall.